Process and system for recovering carbon

ABSTRACT

A process and system for the reduction (by milling), separation and recovery of carbon contained in char, coke and other residues resulting from distillation or destructive distillation of carbon-containing materials. The process or system includes ball or rod mill means for pulverizing incoming carbonaceous materials such as char, routing the output of the mill to a classifier so as to provide for a large particle return, conveying the output of the classifier to a flotation system wherein appropriate reagents are added to effect froth recovery, and finally, thickening the result of the material and otherwise processing it so that a carbon cake may be derived, dried, and deposited for carbon storage. Resultant carbon is thus produced in essentially a pure form, rivaling that derived through current mining processes.

United States Patent 1 1 Brewer Feb. 26, 1974 PROCESS AND SYSTEM FOR RECOVERING Primary Examiner-Granville Y. Custer, Jr.

CARBON [75] inventor: John C. Brewer, Salt Lake City, [57] ABSTRACT U h A process and system for the reduction (by milling), I 1 separation and recovery of carbon contained in char, [73] Asslgnee' Garbalizer (Forporation of America coke and other residues resulting from distillation or Salt Lake Clty, Uta destructive distillation of carbon-containing materials. 22 i F 23, 1973 The process or system includes ball or rod mill means for pulverizing incoming carbonaceous materials such [21 1 Appl 335,009 as char, routing the outputof the mill to a classifier so as to provide for alarge particle return, conveying the 52 us. Cl. 241/21, 241/24 output of the classifier to a flotation system wherein 51 1m. 01.; B02c 21/00 pp p reagents are added to effect froth recov- [58] Field of Search 241/20, 21, 24 y and finally, thickening the result of the material and otherwise processing it so that a carbon cake may [56] References Cit d be derived, dried, and deposited for carbon storage. UNITED STATES PATENTS Resultant carbon is thus produced in essentially a pure 2 903 374 9/1959 Ramse at 24121 form, rivaling that derived through current mining 3,602,437 8/1971 Driscoll 241/21 pmcesses' 14 Claims, 1 Drawing Figure 1z2 WATER lN REAGENTS i 1s 17 22 14 2o CHAR RECEIVING MILL f CONDITIONER AREA FEEDER CONVEYOR- (BALL 0R Rm) (:QNVEYOR QF CLASSIFER CONVEYOR OF GROUND CELL GROUND CHAR CHAR m H2O CARRIER LARGE PARTICLE RETURN 1a 23 35 3| 0 ERFLOW 23 '26. t f

D W 32 PRIMARY 34 22 27 RESIDUE (CARBON CAKE) LIQUID RiZTURN SCREW convsvoa ASH H20 36 CLEAR e v OVER F S liJ A 24 DRYER CARBON TA LlNGS A 4 STORAGE ll s aaaaw e 1' I PROCESS AND SYSTEM FOR RECOVERING CARBON I The present invention relates to the production of carbon and, more particularly, to a process and system capable of receiving carbonaceous residue such as char or coke and processing these residues to separate clays, ash and other foreign matter out from the desired carbon recovery.

Inherent in the system is one or a series of flotation cells, by which foreign material is caused to settle or drop out as residue, whereas carbon particles are recovered by the froth in the flotation system and which froth is subsequently processed through thickener and filter means so that an essentially pure carbon cake is dried, later pulverized if desired, and stored.

In the invention a mill means, in the nature of a rod or ball mill, is used to pulverize incoming char or coke,

so that a majority of the output of the mill will be fine powder, or at least of the order ofa maximum of l/I6th inch particle size or less. Any largechunks of incoming char or cokewhich are not pulverized in the mill are routed back for subsequent processing in the mill through a classifier system.

Means is provided for recirculating water as from a 'tailings pond and at thickener stages to the classifier plete, pulverizing and flotation system for pulverizing incoming material and to derive flecks or particles through a frothing system, the output of the latter being treated to provide a carbon cake that can be stored.

A further object of the invention is to treat the surfaces of carbon and ash particles as to aid in a separationthereof in the flotation sub-system of the invention. I

Another object is to provide a method of treating residues derived from distillation or destructive. distillation wherein carbon content may be derived through other than electrical means.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The present invention, both as to its organization and mannerof operation, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the. sole FIGURE in which:

The sole FIGURE is'a schematic block diagram of the the method and system contemplated by the present invention.

In FIG. 1 the char receiving area 10 may be any designated'are'a, bin, hopper or other structure suitable for collecting materials to be processed. These materials will comprise carbon-including materials, and specifically will comprise materials such as char, coke and other residues as results from distillation or destructive distillation of carbon-containing materials or mixtures.

The subject materials received at char-receiving area or structure 10 will be conveyed by feeder conveyor 11 such as an endless conveyor or screw conveyor. Mill 12 will comprise a tumbler type mill such as a ball mill or rod mill. There may be provided a water inlet 13 such that the materials introduced to the mill I2 will'be ground in aqueous environment. Milling should continue until a majority of materials milled by unit 12 will pass a I/l6th inch screen mesh. In other words, a majority of the material will comprise fines of particulate form in majority of which will not exceedl/loth inch in cross sectional diameter or dimension.

Conveyor 14 may be of the endless. conduit, or screw-conveyor type, designed to feed material into a conventional classifier ISQ Here at the latter may include a water inlet at I6 as well as return water at 17, hereinafter described. The classifier unit I5 of the sole FIGURE may comprise any one of a number of types of classifiers such as the Krebs cyclone-pump unit or another unit used in the industry and going under the name (Dorr-Oliver) Dorrclone by way of example. To the output 18 or classifier 15 is coupled conveyor 19, suitably designed to convey ground char in an aqueous medium to conditioner cell 20. The latter may comprise a flotation tank, a mixing chamber, or simply a vessel into which reagents as at 21 may be introduced as in inlet 22 to mix with the, ground char as carried by the aqueous medium at 19. The suitable reagents that can be used are well known in the copper-concentrate flotation art and will include'kerosene, sodium silicate, and a conventional MIBC. alcohol frother. Thus, a ground char in the H 0 conveyor and the aqueous carrier and with the addition reagents enters into the primary flotation cell 23.

Flotation machines are used in non-analagous art such as the recovery of copper from low grade .ore. A flotation cell or machine is simply a vessel having a special agitation device that mechanically maintains suspension of particulate solids in an aqueous medium while-simultaneously-producing a dispersion of small air bubbles to which particles having hydrophobic surfaces become attached. The latter rise to the surface for availability as a froth-concentrate. During this operation the flotation cell simply settles out ash and clays, which can be carried as by conveyor means 24 to a tailings pond 25. Accordingly, a primary flotation cell 23 may comprise a conventional flotation cell as is used presently in the copper industry; the same consists simply of a vessel having some type of movable stirrer or other suitable means for maintaining a general suspension of particulates within the cell during the flotation process. The frother of the flotation unit produced by the reagents he reinabove described simply provides for the generation of air bubbles to which the small particles of carbon can adhere so that the latter may arise to the surface of the cell.

The latter is drawn off as an output at 26 and is fed to a secondary cell 23, similar to the first but having an agitation unit of reduced movemenLThis can be accomplished simply by reducing the speed of the stirrer, propeller, paddle or other agitation means. The purpose for the reduced agitation of course it to obtain additional separation of the desired carbon particles from ash, clays and silt, for example such that the latter may be removed at outlet 27. To outlet 27 is coupled a pump 28 which pumps the material back into the flotation cell for further processing in a re-cycle type of operation. I

The final end product of the secondary flotation cell 28 is fed to a thickener unit 29. Thickeners or thickener machines, as they are called in the industry, are manufactured currently by the Envirotech Corporation, the Denver Equipment Company, and so forth. The output 31 of thickener 29 is fed through a diaphragm pump 32 which forces a carbon concentrate material through a drum filter 33. The latter is provided with a re-cycling circuit 34, and fresh liquid carrier such as water may be returned from the drum filter and fed to the thickener with the ash being piped to a tailings pond for re-use or disposal. Overflow water from the tailings pond may be piped back through conduit C to the classifier where the water phase may be re-used. It is noted by the liquid-return will supply clear liquid overflow from both the tailings pond at and also from thickener 29.

The refinement offlotation recovery is effected at the secondary flotation cell, wherein the end product is thickened at thickener 29 and, by means of drum filter 33 and dryer 37, will become suitable for carbon storage. Carbon will have purity properties similar to that of mined carbon. Accordingly, the present invention provides a method of producing carbon from char, coke and other residues in a new and entirely unique manner. The process is suitable for inputs of charcoal and other residues resulting from distillation or destruction distillation of carbon-containing materials.

While particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects, and within the true spirit and scope of the invention.

I claim:

1. A system for recovering carbon from feed stock comprising char, coke or other residues containing carbonaceous materials, including, in combination: milling means for receiving such feed stock and physically reducing the same to particulates, flotation cells means coupled to said milling means for froth-separating out carbon particles from said particulates in the production of a carbon-froth output; and means coupled to said flotation cell means for reducing the water content of said froth output to produce a carbonaceous mass.

2. The system of claim 1 wherein said milling means comprise a tumbler mill of one of a class of mills, said class comprising rod mills and ball mills.

3. The combination of claim 1 wherein said system includes a classifier interposed between said milling means and said flotation cell means, and means for routing particles ofa size greater than l/l 6 inch diameter back to said milling means for further physical reduction. l

4. The system of claim I wherein said flotation cell means comprises a primary flotation cell coupled to and followed by a secondary,-quieter flotation cell, and means intercoupled between said flotation cells for conducting residue from said secondary flotation cell back to said primary flotation cell, and residue outlet means coupled to the bottom of said primary flotation 4 cell to an external tailings pond.

5. The combination of claim 1 wherein said water reducing means comprises a thickener coupled to said flotation cell means, a drum filter, pump means interposed between said drum filter and said thickener for conducting the output of the latter to the former, and dryer means coupled to said drum filter for receiving the output of the latterand drying the same, to produce a storable carbonaceous end product.

6. The combination of claim 1 wherein a conditioner, reagent-receiving cell is interposed between said milling means and said flotation cell means.

7. The combination of claim 3 wherein a conditioner, reagent-receiving cell is interposed between said classifier and said flotation cell means.

8. The combination of claim 4 wherein said water reducing means includes a thickener coupled to said secondary flotation cell, said system including a classifier interposed between said milling means and said primary flotation cell, and means for conducting water overflow from said external tailings pond and also from said thickener to said classifier.

9. A method of producing essentially pure carbon from carbonaceous residues such as coke and char, in-

cluding the steps of: providing a carbonaceous residue input feed stock;

milling said-feed stock to particulates a majority of which is less than one-sixteenth inch diameter size;

subjecting said particulates to froth-flotation to produce a carbon-froth output;

thickening said output; and then drying said output to produce a storable carbon cake.

10. The method of claim 9 wherein there is included the additional step of:

conducting residues derived from said froth-flotation step to a tailings pond, and conducting clear liquid from said tailings pond for reuse in the practicing of said method.

11. The method of claim 9 wherein said frothflotation step comprises:

subjecting said particulates, first, to a coarse froth flotation step and then, second, a quieter flotation step, and

conducting the residue output from said quieter flotation step back to said coarse flotation step.

12. The method of claim 9 wherein said milling step comprises milling said feed stock in an aqueous environment.

13. The method of claim 9 wherein, after said milling step, there is included the additional step of classifying the output derived from said milling step to feed oversized particles back to said milling step for further physical reduction.

14. The method of claim 13 wherein there is included the additional step of supplying a water input to said 

2. The system of claim 1 wherein said milling means comprise a tumbler mill of one of a class of mills, said class comprising rod mills and ball mills.
 3. The combination of claim 1 wherein said system includes a classifier interposed between said milling means and said flotation cell means, and means for routing particles of a size greater than 1/16 inch diameter back to said milling means for further physical reduction.
 4. The system of claim 1 wherein said flotation cell means comprises a primary flotation cell coupled to and followed by a secondary, quieter flotation cell, and means intercoupled between said flotation cells for conducting residue from said secondary flotation cell back to said primary flotation cell, and residue outlet means coupled to the bottom of said primary flotation cell to an external tailings pond.
 5. The combination of claim 1 wherein said water reducing means comprises a thickener coupled to said flotation cell means, a drum filter, pump means interposed between said drum filter and said thickener for conducting the output of the latter to the former, and dryer means coupled to said drum filter for receiving the output of the latter and drying the same, to produce a storable carbonaceous end product.
 6. The combination of claim 1 wherein a conditioner, reagent-receiving cell is interposed between said milling means and said flotation cell means.
 7. The combination of claim 3 wherein a conditioner, reagent-receiving cell is interposed between said classifier and said flotation cell means.
 8. The combination of claim 4 wherein said water reducing means includes a thickener coupled to said secondary flotation cell, said system including a classifier interposed between said milling means and said primary flotation cell, and means for conductiNg water overflow from said external tailings pond and also from said thickener to said classifier.
 9. A method of producing essentially pure carbon from carbonaceous residues such as coke and char, including the steps of: providing a carbonaceous residue input feed stock; milling said feed stock to particulates a majority of which is less than one-sixteenth inch diameter size; subjecting said particulates to froth-flotation to produce a carbon-froth output; thickening said output; and then drying said output to produce a storable carbon cake.
 10. The method of claim 9 wherein there is included the additional step of: conducting residues derived from said froth-flotation step to a tailings pond, and conducting clear liquid from said tailings pond for reuse in the practicing of said method.
 11. The method of claim 9 wherein said froth-flotation step comprises: subjecting said particulates, first, to a coarse froth flotation step and then, second, a quieter flotation step, and conducting the residue output from said quieter flotation step back to said coarse flotation step.
 12. The method of claim 9 wherein said milling step comprises milling said feed stock in an aqueous environment.
 13. The method of claim 9 wherein, after said milling step, there is included the additional step of classifying the output derived from said milling step to feed oversized particles back to said milling step for further physical reduction.
 14. The method of claim 13 wherein there is included the additional step of supplying a water input to said classifier step. 